According to a known ottoman device disclosed in 2000-201772A a posture of an ottoman main body can be adjusted between a stored state and an extended state by moving a nut in a front-rear direction of a seat by rotating a screw that is positioned under the seat, and by oscillating a main link, which is connected to the nut, and rotation link, which comprises a link device.
Because the ottoman device has the screw in order to adjust and support the position of the ottoman main body, a large space needs to be provided under the seat in order to store the ottoman main body. However, if the space is limited and a distance from the vehicle floor to a seating surface of the seat needs be reduced, it becomes difficult to store such ottoman device under the seat.
Further, the ottoman device has a structure in which two rotation links and the main link support an excessive external force, which is applied to the ottoman main body in a front direction or a downward direction thereof. In such case, the nut is engaged with the screw so as not to move in a front-rear direction of the seat, however, because the main link is connected to the nut so as to be rotatable, when the external force is applied to the ottoman main body in a front direction, the ottoman main body is supported and the posture of the ottoman main body is maintained only by use of a rigidity of the link. This happens because all links are rotatably connected and not locked each other at a specific portion. Thus, in order to secure a supporting strength of the ottoman main body, each link needs to be thickened substantially.
Further, in order to extend the ottoman main body at an upward position, longer rotation links need to be provided and a pitch between the rotation links needs to be shortened. Thus, it becomes more difficult to maintain the posture of the ottoman main body.
A need thus exist to provide an ottoman device that secures the supporting strength of the ottoman main body appropriately.
Another ottoman device disclosed in JP06-031967Y extends an ottoman main body stored under the seat in a front direction thereof by means of a four-link mechanism. Specifically, the ottoman device includes a mechanical lock device (a shaft lock device) having a compressed spring by which the top end portion of the ottoman main body is connected to a bottom portion of a seat cushion. When the mechanical lock device is unlocked by means of a release lever (an operation portion), the ottoman main body is oscillated and extended in a font direction of the seat. On the other hand, when the ottoman device is in an extended state and unlocked by means of the release lever, the ottoman main body is oscillated and stored under the seat.
In this configuration, because the ottoman main body is rotated when its position is changed from the stored state to the extended state, the compressed spring is elongated in accordance with the extension of a rod of the lock device, and the biasing force (spring force) becomes smaller.
On the other hand, as shown in FIG. 2 and FIG. 5 of JP06-031967Y, comparing an angle between a rotational center A1 (a rotational center B1) and a working direction of the compressed spring when the ottoman main body is in an extended state, and the angle when the ottoman main body is in a stored state, these angles are approximately the same, or the angle in the extended state is less than the angle in the stored state.
Further, in order to lift up the ottoman main body by use of the biasing force of the compressed spring (in order to extend the ottoman main body), a torque in the vicinity of the rotational center (A1 or B1) on the basis of the biasing force when the ottoman main body is in an extended state is set to be equal to or more than the ottoman main body's weight moment.
Thus, when the ottoman main body is stored manually, the biasing force becomes larger in accordance with the compression of the compressing spring, a large operation force is required to store the ottoman main body.